1. Field of the Invention
The present invention relates to an improved electrolyzer suitable for the manufacture of electrolyzed water having a sterilizing power and for purification and filtration of water, such as waste water, water used with raising fish bath and pool water, cooling water, water used in sewage processing, and the like.
2. Description of Related Art
Electrolyzers used to manufacture electrolyzed water such as described above form functional water (alkali ion water and strong acid water). Such electrolyzers typically employ a ferrite electrode to which an electrode terminal is formed through a conductive bond as an anode because it needs only a small processing current and electrolysis can be performed using a partition wall interposed between the ferrite electrode and a cathode.
In order to form weakly acid or neutral sterilizing/rinsing water and for the purification and sterilization of waste water and various kinds of water, a large processing current is typically required. Accordingly, when a ferrite electrode is used as described above, the conductive bond between the electrode terminal and the ferrite electrode is removed therefrom due to the difference between their respective coefficients of thermal expansion because they are repeatedly heated and cooled, and due to the resistance of the coupling portion increased by the conductive bond. As a result, the coupling resistance is increased by the invasion of water into the interval between the conductive bond and the ferrite electrode and the electrode terminal as well as the fact that the conductive bond becomes eluded into electrolyzed water and is made unusable at once because it has bad chemical resistance.
To cope with the above problem, electrolysis has been executed using a platinum-plated titanium electrode which has platinum plated on the surface of titanium without using a partition wall because an electrode terminal can easily be formed from titanium by welding, screw cutting or the like and titanium is less eluded in electrolysis.
A reason why the above platinum-plated titanium is used as an anode is that platinum, ferrite, lead and titanium have higher resistance to elusion in the above order and the expensive platinum has the highest elusion resistance in the above metals. However, when a platinum-plated titanium electrode is used and the voltage imposed on the electrode and a processing current is increased, a problem arises that the plated platinum becomes exfoliated, titanium is eluded, and the anode electrode becomes corroded.
Therefore, to prevent the exfoliation, an electrolyte such as salt or the like must be added to the water to be processed by the electrolyzer to increase the conductivity of the water.